Diseased trees?
I have what I think are crab apples. They have not grown in 6 yrs I have been here. It blooms every year though. Live in central Ohio. Is it a fungus?
First thing Jbitter...they are not diseased. That is lichen on your tree. A plant similar to moss..and a sure sign of clean , moist, air.
Does no harm at all.
If your tree has ceased to grow then there are several reason that could be the cause.
It may be on a dwarfing stock and it's reached it's full height.
Your soil is not that good, too wet, poor nutrition. Etc.
You are not pruning it to encourage new growth.
The leaf and shoots that can be seen on your photos look quite healthy.
As to fruiting.
If your tree is not producing any fruit at all....even tiny ones...then there is a pollination problem.
Malus fruits vary from very small to large plum size according to variety.
Does no harm at all.
If your tree has ceased to grow then there are several reason that could be the cause.
It may be on a dwarfing stock and it's reached it's full height.
Your soil is not that good, too wet, poor nutrition. Etc.
You are not pruning it to encourage new growth.
The leaf and shoots that can be seen on your photos look quite healthy.
As to fruiting.
If your tree is not producing any fruit at all....even tiny ones...then there is a pollination problem.
Malus fruits vary from very small to large plum size according to variety.